Quantum dot (nano-scale) lasers are lasers embedded in quantum dot cavities. The lasers emit coherent light within a narrow range of wavelengths. The power and noise level of a given quantum dot laser depends, in part, on the size of the quantum dot cavity which generates the laser. Quantum dot cavities typically differ at least slightly in size from one another. Due to the tiny sizes of the quantum dot laser, it is difficult to make them uniform in size. This means that power and noise levels may not be uniform among quantum dot lasers.
Because of the nature of quantum dot lasers, individually they generally have lower noise levels than traditional lasers, but they also have lower power. The noise level of light emitted from quantum dot lasers generally is directly related to the size of the quantum dot cavity which, in turn, is generally related to the power of the quantum dot laser. Thus, a larger quantum dot cavity will produce a laser emitting coherent light with higher power than a smaller quantum cavity, but the more powerful laser will also have a higher noise level. Additionally, since it may be difficult to control the size of the quantum dot cavities, a wider range of wavelengths than desired may result, which also increases the accompanying overall noise levels. The trade-off between power and noise levels in quantum dot lasers limits the uses to which the lasers can be put, as many applications requiring low noise levels also require high power.